In your case I would rather suggest using the inclusion option, rather than the exclusions, it's much more convenient – as you only need items regarding one category only. You can find that on the Advanced Options -> Exclude results panel: https://i.imgur.com/0TAaPOu.png

This however will still include results which does not have any categories or have no connection with the chosen category. To bypass those as well, turn this option off too: https://i.imgur.com/wvoDjPm.png

This will make sure that only items belonging to the chosen category will be displayed, regardless if they have any other taxonomy term relations.

Best,Ernest MarcinkoIf you like my products, don't forget to rate them on codecanyon :)